1. Field of the Invention
The present invention relates to a sequencer unit of electronic musical instrument, and more particularly to a sequencer unit of electronic musical instrument in which a plurality of sequencers can be changed over in response to a player's will with ease.
2. Prior Art
As an additional unit for automatically playing a performance in the electronic musical instrument, a sequencer unit is well known as disclosed in Japanese Patent Laid-Open Publication No. Sho 61-174599 (entitled: "Performance Data Processing Apparatus"), U.S. Pat. No. 4,062,263 (entitled: "Automatic Rhythm Performing Apparatus") and Japanese Patent Laid-Open Publication No. Sho 53-70421 (entitled: "Automatic Accompaniment Apparatus"), all of which were filed by the present applicant, for example. The above performance data processing apparatus is a chord sequencer by which chord data are written in and read from the memory so as to output data changed in response to a predetermined accompaniment pattern, and the read data are used as automatic accompaniment data for the electronic musical instrument, for example. In addition, the above automatic accompaniment apparatus automatically plays a rhythm performance having a desirable rhythm pattern when the main performance is ended.
In the conventional techniques described above, a plurality of sequencers (or memory means) are provided. However, the conventional techniques do not refer to operations thereof when the sequencers are changed over. In the chord sequencer which records (or writes in) and reproduces the chord data as the performance data, two or more bars are frequently repeatedly performed (i.e., repeat reproduction is frequently executed). Meanwhile in the case where the writing is ended at a certain timing in a sequencer writing cycle in the conventional chord sequencer, the music is reproduced till the certain timing and then the reading returns back to head data. For this reason, the certain timing is not synchronized with the bar, so that the notes must be shifted at every time when the reproduction is repeated. Thus, the conventional chord sequencer suffers a disadvantage in that the player must pay great attention to the timing of depressing a writing end switch.
On the other hand, in the conventional automatic rhythm performance apparatus, it is not possible to take a break (i.e., a non-rhythm state) having an arbitrary period in the rhythm performance. In order to take such a break, it is possible to adopt a method in which a rhythm start switch is operated to thereby temporarily stop generating the rhythm and then the rhythm is re-started at an arbitrary timing as disclosed in the Japanese Patent Publication No. Sho 59-31077. At re-starting, a tempo clock must be reset, and the conventional automatic rhythm performance apparatus suffers a disadvantage in that a timing of section must be shifted in the re-started rhythm.
Hereinafter, the word "section" will be defined by a quarter period of one bar of 4/4 time, or one third period of one bar of 3/4 time, for example. In other words, there are four sections, i.e., first to fourth sections in one bar of 4/4 time, and there are three sections, i.e., first to third sections in one bar of 3/4 time.
By combining the above three conventional techniques together, it is possible to design so that the accompaniment pattern will be changed to the desirable ending pattern at the ending timing thereof. When the ending pattern is selected as the chord read from the chord sequencer changes "C", "Em" to "D7", the accompaniment chord must be changed "C", "Em" to "D7" similarly. Such phenomenon is not preferable.